Silent chain



NGV. 26, 1940. Q 'A CUMFER 2,223,314

SILENT CHAIN Filed Marchv 23, 1940 4 mam# ATTORNE l Patented Nov. 26, 1940 PATENTN oFFicE SILENT CHAIN i Donald A. Cumfer, Ridgewood, N. J., assignor to Willcox & Gibbs Sewing Machine Company, New York, N. Y., a, corporation of New York Application March 23, 1940, Serial No. 325,488

14 Claims.

This invention relatesjto chains, and especially to so-called silent drive chains constructed from links.

' Drive chains constructed of links are in general use on many types of machines and apparatus. Ordinarily link chains are quite noisy, but silent chains have been constructed of materials such Ias pressed flberboard. In spite of their advantage of quiet operation, iiberboard chains have not been extensively adopted, partly because their period of useful life is so very `much shorter than the life of a metal chain.

In the past chain manufacturers and users have had great difficulty in properly lubricating chains. Splash, pump, drip, spray, and hand oiling have all been tried, but thousands of dollars are still being lost annually because of breakdowns or failures resulting from unsatisfactorily lubricated chains.

'I'he Weight and balance of a chain aiects its usefulness and life considerably. The replacement costs of a chain drive include not only the chain but also the sprockets, which are worn away by the constant noisy beating and weigh-t of a steel chain.

An object of this invention is to provide a silent chain having a very Along period of usefulness. Another object is to provide a chain capable of going relatively long periods, of time Without lubrication.

Further objects include: the provision of a link chainhaving a small weight in comparison to other chains of the `same'width; and the provision of nonmetallic members in the chain to reduce wear upon the sprocket.

A' feature of the present invention is the use of metallic shrouds,'thereby furnishing wearresisting guide plates to keep the chain upon the sprocket,and particularly the arrangement of the metallic shrouds so as 4to contribute to the balance, tensile strength, and life of the chain. The metallic shrouds alsofcooperate with metallic links lto provide metallic connections running continuously throughout the length of the chain.

Another feature is the use of links made of nonmetallic material in a balanced arrangement lrelativeto cooperating metallic links so that noise is greatly reduced.

Other features of this invention include the use ofa material for the nonmetallic links which has: certain resiliency `so that the sprocket is worn very slowly; a high tensile strength to increase the life of the belt; a sound deading quality; and, of special importance, the property of absorbing lubricating oil without materially im- (ol. 'i4-243) pairing the acoustical, strength properties thereof.

Yet another feature of much importance is the use of metallic links inthe chain in addition to and in conjunction with the nonmetallic links. These metallic links, by themselves, and/or with the metallic shrouds, form a continuous band of metallic strength through the chain, thereby greatly adding to the life of the chain, but without materially impairing the quietness resulting 10 from the use of the nonmetallic links.

Another feature of the present invention is the provision of an odd number of alternate laminae of metallic and nonmetallic links, or group of links, thereby .assuring better distribution of oil 15 to the metallic links. A further feature is the provision of a balanced arrangement of metallic and nonmetallic linksfwith metallic shrouds to insure a uniform weight and strength throughout the length of the chain.

Other objects and features will appear hereinafter.

In the drawing:

Figure 1 shows a top view of one embodiment of this invention.

Fig. 2 is a side view of Fig. 1.

Fig. 3 is a top View of another chain embodying this invention.

Before describing .the present improvements and vmode of operation thereof in detail it should be understood that the invention is not limited to the details of construction and arrangement of parts shown in the accompanying drawing, which are merely illustrative of the present preferred embodiments, since the invention is capable of other embodiments, and the phraseology employed is for the purpose of description and not of limitation.

Referring now in detail to the drawing, and

resilient, or tensile particularly to Figs. 1 and 2, there is shown am,y

chain 8 including a plurality of pins ID flattened at each end to form retaining heads I I. Metallic shrouds I2 adjacent the retaining heads II form the outer connecting links between certain of the pinsand` have guard sections I3 designed to prevent the chain from having undue -sideslip upon thesprocket. Metallic links I4 adjacent to the shrouds, and'iconnecting the pins, are provided with holes I5 which are preferably elongated. In the embodiment illustrated, the metallic linksl I4 are used only to join pins not connected to each other by means of shrouds I2. The shrouds I2 and links I4 form two continuous groups of connectors I6 and `I'l of metallic strength throughout the length of the chain and form the outside y'-" shrouded sets by means of the pins of the l shrouded sets. The continuous chain is constructed of shrouded sets and unshrouded sets spaced alternately and in balanced relation to each other. i

A group of nonmetallic connectorslmade up of a plurality of nonmetallic links |9"'and 2|J`is` interposed between the groupswof metallic 4connectors I6 and II to form a continuous run of nonmetallic toothed links centrally longitudinallyr disposed. The links I9 and 2li are connected` to and pivot about the pins I0, The link I9 compares in shape tothe link T4, each lhaving holes 2| which are preferably elongated. The links I9 are used to connect pins not joined together by shrouds I2 and are members of unshrouded sets. The links 20 are similar to the links I9 by having gear teeth 23 of appropriate design. ,However, each end of the links 2li has a hole 24, preferably round, adapted to recevea pin ID. Links 2l] are used to connect pins I0 joined by shrouds I2 and are, therefore, members of shrouded sets.

Now of particular importance, and acording to the present invention, it should be noted that the links I9 and 2|3are made of nonmetallic material. Quietness of operation is assured by selecting for the material for the links I9 and 20 a substance having acoustical properties that it will deaden sound appreciably. The surprising phenomena of a chain having metal teethl being quiet inlopervation is believed to be partly explained by the fact that the nonmetallic links absorb and deaden the noise produced bythe clashing of metal teeth. f

Another important property of the material used for the linksvIQ and 25 is its oil-absorbing property. Many chain failures have been caused by faulty lubrication. By the use of a material which absorbs and retains- ,oil for some period of time, it is possible for the chain to operate sorbed upon and within the links IQHand 2U. The lubrication can be much less frequent` when oilabsorbing nonmetallic links I9.gand 2|] are used than has been true for any of the usual types of chains capable of transmitting an equal amount of power. f i

The material used for the links I9 and 20 is preferably somewhat resilient,` and able to cushion the blow when struck by the sprocket teeth, thereby lengthening the life of both the sprocket and the chain. Because of thernetallic connectors I6 and I'I the tensile strength of the material used for the links I9 and 20 is not of as great importance as it is if the chain were made entirely of nonmetallic links. It isdesirable to use the highest tensile strength obtainable without too great a sacriiice in sound-absorbing, oil-absorbing, and resilient properties.

According to the present` invention the nonmetallic links are preferably made from sheets of modern synthetic plastic, particularly that type sold commercially as Micarta'f Materials including sheets of cloth bonded Iunder great `pressure with a suitable plastic binder are very satisfactory for the nonmetallic links.

In Fig. 3 the pins I0, head II, shrouds I2, guard plates I3, metallic links I4 and nonmetallic links I9 and 20 are the same as in Fig. 1. A metallic link 2|, similar in shape to the nonmetallic link 20, is designed to connect pins joined by shrouds. In Fig. 3, however, there is illustrated a chain differing from the arrangement of the groups of links'l, I1 and I8. Instead of having nonmetallic links I9 and 20 in `the center, the form of the invention illustrated in Fig. 3 has metallic links I4 and 2| in the center, with nonmetallic links I9 and 20 on each side thereof. A group of metallic connectors 22, made up of metallic links I4 and 2|, is interposed between two groups of nonmetallic connectors 23 and 24, made up of nonmetallic links IS and The shrouds I2 form part of two uncompleted groups of connectors 25 and 26. Unless a wide chain is desired, it is deemedvpreferable to leave groups 25 and '26 uncompleted, and to Yuse only three completed groups. chains,l however, nine,A eleven or any4 other number of alternate metallic groups and nonmetallic groups might be used. This form of the invention has the same advantage as the rst form; viz., each of the sets are of substantially the same weight to insure quiet and long running (e. g., where two thick metallic links are provided in alternate sets no shroud plates are provided and in the alternate sets wherel onlyone thick metallic link is used a pair of thin' shroud plates is provided). It should be noted thatthe present structure achieves a balanced vchain inasmuch as each shrouded set has substantially the same Weight as each unshrouded set in the same chain (e. g., two nonmetallic links plus two thick metallic links in the nonshrouded sets are substantially the same in weight as the otherI alternate shrouded sets which include three nonmetallic links and two thin metallic shroud plates). Each' shrouded Iset has fewer metallic links than the unshrouded sets to compensate for the weight of the metallic shrouds. f

The balanced chain makes possible a smooth, quiet operation and gives a long period of usefullife. Also, itsh'ould be noted that the alternate sets of metallic shroud plates and intermediate metallic toothed links provide two continuous runs olf-metallic members, one at each side of the chain to eiectively maintain the chain at its original length and to prevent adverse wear on the pin holes of the nonmetallic links therebe- For very wideshroud plates; and means connecting said metaland means interconnecting metallic and nonmetallic links to form alternate unshrouded sets and for concurrently connecting nonmetallic links and shroud plates to form alternate shrouded sets, with the shrouded and unshrouded sets of substantially the same weight.

4. Inasilent chain the combination of nonmetallic toothed links; a plurality of pins connecting said links together in a continuous chain; only metallic shroud plates and nonmetallic toothed links with a pair of pins forming alternate shrouded sets in the silent chain; and only metal and nonmetallic toothed links connected to and intermediate the pins of said shrouded sets.

5. In a silent chain the combination of a plurality of centrally longitudinally disposed nonmetallic toothed links; a plurality of outwardly disposed metallic toothed links and shroud members; and pins interconnecting all of said central nonmetallic and said outward metallic members. 6. In a silent chain the combination of a continuous run of metallic toothed links through the center of .the silent chain; continuous runs of nonmetallic toothed links adjacent said central run of metallic toothed links; and -pins connecting said 'continuous runs of metallic and nonmetallic toothed links together.

'7. In a silent chain the combination of nonmetallic links; a plurali-ty of pins connecting said nonmetallic links together in a continuous chain; pairs of metallic shroudplates connecting pairs of pins to form gapped and completely separated shrouded sets; and metallic links closing the gaps and extending from one shrouded set to another.

8. In a chain .the combination of metallic toothed links; nonmetallic toothed links; metallic shrouds; and pins.

9. In a chain the combination of a `plurality of metallic pins; a plurality of pairs of metallic shrouds connecting the ends of said ypins to comprise shrouded sets; a plurality of toothed nonmetallic links made of a rigid synthetic material absorbing lubricating oil, positioned adjacent said shrouds; and a lplurality of toothed metallic links, positioned adjacent to and between the nonmetallic links.

10. In a silent chain thecombination of a continuousinterconnected alternate single and double center run of toothed metallic links; a continuous run of interconnected nonmetallic toothed links adjacent said single and double metalic links; pins, and alternate pairs of shroud plates forming shrouded sets. Y

11. In a silent chain the combination of metallic pins; metallic shrouds; a continuous center run of toothed metallic links; continuous outside runs of toothed nonmetallic links made of stii, resilient, synthetic, oil absorbing material; and means connecting said metallic links, nonmetallic links and shrouds together.

12. In a chain the combination of a plurality of nonmetallic links made of Micarta and arranged to form the central portion of a chain; a plurality of metallic links; a plurality of metallic shrouds, said metallic links and metallic shrouds being arranged beside said nonmetallic links to form the outer Iportions of a chain; and a -plurality of pins connecting said metallic links, nonmetallic links and shrouds.

13. In a silent chain the combination of unshrouded sets comprising two kinds of toothed links made of two materials of diffe-rent specific gravity; shrouded sets of substantially thesame weight as the unshrouded sets, said identical weight being achieved by the use of suitable proportions of said two materials of different specific gravity; and pins connecting said shrouded and unshrouded sets together.

14. In a silent chain the combination of shrouded sets consisting of toothed links and metalic shroud plates; unshrouded sets consisting of nonmetallic 4toothed links made of stiff resilient oil absorbing synthetic plastic material, and metallic toothed links in such proportions that the weight of an unshrouded set is substantially the same as that of a shrouded set, the links of said unshrouded set having elongated holes; the nonmetallic toothed links forming a continuous run of nonmetallic connectors; the metalli-c links and shrouds forming a continuous run of metallic connectors; and pins connecting said shrouded and unshrouded sets together.

DONALD A. CUMFER. 

